Manufacture of tobacco smoking products



United States Patent" MANUFACTURE OF TOBACCO SMOKING PRODUCTS Walter G. Frankenburg, Millersville, Pa., and Peter H. Waltz, Auvernier Nenehatel, Switzerland, assignors to General Cigar Co., Inc., New York, N.Y., a corporation of New York No Drawing. Filed May 24, 1955, Ser. No. 510,851

21 Claims. (Cl. 131133) This invention relates to tobacco products adaptedfor smoking, and more particularly to smoking products comprising comminuted tobacco and a water-soluble cellulose derivative;

While tobacco sheets made exclusively of dry-ground and low tensile strength.

These undesirable eifects are frequently encountered in sheets made of tobacco dust originating from cigarette tobacco,'a1though some types of cigar tobaccos, particularly dark tobaccos such as those from Brazil and San Domingo, are also troublesome.

The principal object of this invention is to improve the physical properties of sheets and other coherent bodies produced from comminuted tobacco and a water-soluble cellulose derivative as binding agent.

' In'accordan'ce with this invention, to powered tobacco which is admixed with a highly viscous aqueous solution of a water-soluble cellulose derivative to form a paste, there is added a controlled amount of acid, usually not exceeding about 5% based on the weight of the powdered tobacco alone. The amount of acid employed depends on the nature of the particular tobacco in the aqueous suspension or paste. Unless the tobacco is one which tends to give a very dark colored or very weak sheet or like coherentbody, an addition of acid corresponding to approximately 2 or 3% by weight of the tobacco will give a distinctly improved product. Dependingon the amount of acid added and on the buffering capacity of the tobacco, the acidic aqueous paste will usually have a pH in the range of 3.0 to 5.5.

The acid may be organic or inorganic but preferably is one which is not' strongly oxidizing. Illustrative acids usefulin this invention 'are malic, citric, tartaric, phosphoric and boric acids. Acids containing sulfur, selenium, tell'ilriurn, nitrogen, arsenic, the halogens and like elements which during combustion of the tobacco product would give ofl obnoxious smoke components or would impair the burning of the tobacco are to be avoided. Inasmuch as citric acid is naturally present in some high quality tobaccos, this acid is often selected for addition to the aqueous suspension of tobacco powder. Furthermore, citric acid has been found effective in improving the color, aroma and strength of sheets and like coherent bodies made with various types of tobacco.

The water-soluble cellulose derivatives used in accordance with this invention are the non-salt type, i.e., ex-- solution.

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clude salts like sodium carboxymethyl cellulose. Illustrative non-salt type derivatives are methyl cellulose, hydroxyethyl cellulose, methyl hydroxyethyl cellulose and methyl hydroxypropyl cellulose. Preferably, as set forth in the aforesaid patent of Frankenburg and Garbo, the water-soluble cellulose derivative is of such grade or polymeric character that'not more than about 2% by weight thereof, when dissolved in water, yields a solution having a viscosity of at least 1500 centipoises at a temperature of 25 C. Very satisfactory results are generally obtained with grades of water-soluble cellulose derivative which give a viscosity of approximately 4000 centipoises at a temperature of 25 C. when 2% by weight is dissolved in water. As also brought out in the aforesaid patent of Frankenburg and Garbo, it is advantageous to admix the dry-ground tobacco with an aqueous solution of the cellulose derivative which has "a viscosity of at least 1500 centipoises at a temperature of 25 C.

The order in which the ingredients of the products of this invention are brought together may be varied. Usually, the binding agent is first dissolved in water and the other ingredients are then added to the aqueous solution. Besides the tobacco power and small amount of acid, the other'ingredients may include a plasticizer such asglycerine, sorbitol and the glycols, minenal-type fibers, diatomaceous earth and a non-water-swelling siliceous catalyst as disclosed in U.S. Patent 2,706,695 of Frankenburg, issued April 19, 1955. It is generally advisable to add the tobacco powder and acid .to' the aqueous solution of the cellulose derivative after the other desired ingredients have been admixed with the The best products of this invention include plasticizers and siliceous catalysts.

In the interests of better understanding and greater clarity, illustrative embodiments of the invention are presented hereinbelow in detail. In these examples, which are not to be construed in any restrictive sense, the proportions mentioned are all based on a common weight unit.

- Example 1 To a solution having a viscosity of 4,000 centipoises measured at a temperature of 25 C. and consisting of 15 parts of methyl cellulose and 750 parts of water,

belt that travels through a drying chamber in which hot air contacts the wet tobacco layer. The temperature in the dryer does not exceed 55 C. and the wet tobacco layer is converted during its passage through the dryer to a coherent sheet, approximately 0.08 millimeter thick. The thus produced tobacco sheet has a light golden brown color, a pleasant aroma and a uniform appearance free of cracks. The tensile strength of the tobacco sheet approximates that of a good quality tobacco leaf.

When the foregoing operations are repeated with the sole exception that the addition of the citric acid is omitted, the resulting tobacco sheet has a muddy olive green color, an aroma unlike that of good tobacco and many cracks running throughout the sheet.

Example 2 To a solution having a viscosity of 4,000 centipoises at a temperature of 25 C. and consisting of 10 parts of methyl cellulose and 500 parts of water, there are added 20 parts of diethylene glycol and 6 parts of powdered siliceous catalyst made by. calcining a silica gel containing about 11% by weight of alumina. To this aqueous mixture, 100 parts of pulverized tobacco are added. The pulverized tobacco consists of 35% of scrap and 35% of stems, both derived from flue-cured tobacco, and 30% of dust obtained from the blending of cigarette tobaccos. A solution of 2 parts of tartaric acid in 5 parts of water is stirred into the aqueous suspension of tobacco powder and the resulting admixture is converted into a sheet as already described in Example 1. The finished tobacco sheet has a golden yellow color, a typical tobacco aroma, and satisfactory tensile strength.

When the operations of this example are repeated with the sole exception that the addition of tartaric acid is omitted, the tobacco sheet thus obtained has a dark brown color and a somewhat unpleasant aroma.

Example 3 One part of a synthetic mineral fiber is shredded and dispersed in a solution consisting of 12 parts of methyl cellulose and 500 parts of water. The aqueous solution of methyl cellulose has a viscosity appreciably higher than 4,000 centipoises at a temperature of 25 C. The other ingredients which are added to the suspension of fiber in the aqueous solution of the binding agent are 20 parts of triethylene glycol, 6 parts of diatomaceous earth and 6 parts of the siliceous catalyst set forth in Example 2. The final additions to the aqueous mixture are 100 parts of Java tobacco ground to pass through an SO-mesh screen and 3 parts of malic acid dissolved in 6 parts of water.

The resulting tobacco paste is converted into a sheet as set forth in Example 1. The tobacco sheet has a brown color, uniform appearance and texture, and a typical Java tobacco aroma.

When the operations of this example are repeated with the sole exception that the addition of malic acid is omitted, the resulting tobacco sheet is almost black and has many cracks. Tensile strength measurements show that the sheet made with the acidic paste has a strength more than 7 times that of the sheet made without the acid.

Example 4 To a solution having a viscosity of 4,000 centipoises at a temperature of 25. C. and consisting of 8 parts of methyl cellulose and 400 parts of water, there are added 20 parts of a polyethylene glycol, 10 parts of diatomaceous earth and 6 parts of the siliceous catalyst used in Example 1. The final additions to this aqueous mixture are 100 parts of pulverized cigarette tobaccos (all passing through an SO-mesh screen) and 5 parts of phosphoric acid (85% H PO diluted in 10 parts of Water. The pulverized tobaccos consist of 35 of Turkish tobacco dust and 65% of stems of flue-cured tobacco.

The tobacco paste is converted into a sheet as described in Example 1 and the tobacco sheet thus obtained has a light yellow color, a typical Turkish tobacco aroma and no cracks.

When the operations of this example are repeated with the sole exception that the addition of phosphoric acid is omitted, the resulting tobacco sheet is badly cracked and has an olive green color and an aroma somewhat foreign to that of tobacco.

While the organic acids useful in this invention embrace such simple carboxylic acids like acetic acid, it is well to note that some acids like propionic and butyric acids are undesirable because of their strong odors. For this reason, polybasic acids, especially those containing one or more hydroxyl groups are generally favored as illustrated in the preceding examples.

Those skilled in the art will visualize many other modifications and variations of the invention set forth hereinabove without departing from its spirit and scope. Accordingly, the claims should not be interpreted in any restrictive sense other than that imposed by the limitations recited within the claims.

What is claimed is:

1. In the manufacture of tobacco smoking products from exclusively dry-ground tobacco and a water-soluble cellulose derivative of the non-salt type used as a binding agent for said dry-ground tobacco, the improvement of uniformly admixing water, said dry-ground tobacco, said cellulose derivative, and a minor amount of acid of the class consisting of phosphoric, boric and hydroxylated polybasic carboxylic acids.

2. The process of claim 1 wherein the exclusively dryground tobacco is of the class consisting of flue-cured tobacco and tobacco from Brazil, Java, San Domingo and Turkey.

3. The process of claim 1 wherein the acid is citric acid and the minor amount of said citric acid does not exceed 5% based on the weight of the dry-ground tobacco.

4. The process of claim 1 wherein the acid is phosphoric acid and the minor amount of said phosphoric acid does not exceed 5% based on the Weight of the dryground tobacco.

5. In tobacco smoking products made of exclusively dry-ground tobacco, the improvement of a binding agent as a component of said smoking products comprising a water-soluble cellulose derivative of the non-salt type in film form and an acid uniformly dispersed in said film to improve the appearance of said smoking products, said acid being of the class consisting of phosphoric, boric and hydroxylated polybasic carboxylic acids.

6. The tobacco smoking products of claim 5 wherein the exclusively dry-ground tobacco is of the class consisting of flue-cured tobacco and tobacco from Brazil, Java, San Domingo and Turkey.

7. The tobacco smoking products of claim 5 wherein the acid is an hydroxylated polybasic carboxylic acid used in an amount not exceeding 5% based on the weight of the dry-ground tobacco.

8. The tobacco smoking products of claim 5 wherein the water-soluble cellulose derivative is methyl cellulose and the acid is citric acid.

9. The tobacco smoking products of claim 5 wherein the water-soluble cellulose derivative is methyl cellulose and the acid is phosphoric acid.

10. An improved tobacco smoking product comprising a predominant proportion of exclusively dry-ground tobacco, a minor proportion of a Water-soluble cellulose derivative of the non-salt type capable of forming a solution with a viscosity of at least 1,500 centipoises at a temperature of 25 C. when not more than about 2% by weight of said cellulose derivative is dissolved in water, said cellulose derivative functioning to hold the particles of said tobacco together as a coherent mass, and a minor proportion of an acid dispersed throughout said coherent mass, said acid being of the class consisting of phosphoric, boric and hydroxylated polybasic carboxylic acids.

11. The tobacco smoking product of claim 10 wherein the exclusively dry-ground tobacco is of the class consisting of flue-cured tobacco and tobacco from Brazil, Java, San Domingo and Turkey. a

12. The tobacco smoking product of claim 10 wherein the acid is an hydroxylated polybasic carboxylic acid and the minor proportion of said acid does not exceed about 5% based on the weight of the dry-ground tobacco.

13. The tobacco smoking product of claim 12 wherein the Water-soluble cellulose derivative is methyl cellulose used in an amount corresponding to about 8 to 15% of the weight of the dry-ground tobacco.

14. The tobacco smoking product of claim 10 wherein the water-soluble cellulose derivative is methyl cellulose and the acid is phosphoric acid.

15. In the manufacture of tobacco smoking products wherein exclusively dry-ground tobacco is admixed with an aqueous solution of a water-soluble cellulose derivative of the non-salt type to form a paste and said paste is converted into dry coherent bodies useful as tobacco smoking products, the improvement of adding acid to said paste to adjust the pH of said paste to the acid range, before said paste is converted into said coherent bodies, to enhance the physical properties of said coherent bodies made from said paste, said acid being of the class consisting of phosphoric, boric and hydroxylated polybasic carboxylic acids.

16. The process of claim 15 wherein the exclusively dry-ground tobacco is of the class consisting of fluecured tobacco and tobacco from Brazil, I ava, San Domingo and Turkey.

17. The process of claim 15 wherein the acid range extends from pH 3.0 to pH 5.5.

18. A coherent tobacco product made from tobacco particles and a viscous aqueous composition of a cellulose derivative of the non-salt type characterized by a pH in the acid range of pH 3.0 to pH 5.5.

19. The coherent tobacco product of claim 18 wherein the cellulose derivative of the non-salt type is methyl cellulose.

20. In the manufacture of a tobacco sheet, the method characterized by forming a viscous aqueous composition of a cellulose derivative of the non-salt type, adding tobacco to said composition to form a dispersion, and adjusting the acidity of said dispersion to a pH in the acid range of pH 3.0 to pH 5.5.

21. The method of claim 20 wherein the cellulose derivative of the non-salt type is methyl cellulose and the adg'ustment of the acidity of the dispersion is effected by the addition of an hydroxylated polybasic carboxylic acid.

References Cited in the file of this patent UNITED STATES PATENTS 2,433,877 Wells et al. Jan. 6, 1948 2,598,680 Frankenburg June 3, 1952 2,613,673 Sartoretto et a1 Oct. 14, 1952 OTHER REFERENCES Gortner: Outlines of Biochemistry, page 598. Published 1929 by John Wiley and Sons, Inc. New York. 

1. IN A MANUFACTURE OF TOBACCO SMOKING PRODUCTS FROM EXCLUSIVELY DRY-GROUND TOBACCO AND A WATER-SOLUBLE CELLULOSE DERIVATIVE OF THE NON-SALT TYPE USED AS A BINDING AGENT FOR SAID DRY-GROUND TOBACCO, THE IMPROVEMENT OF UNIFORMLY ADMIXING WATER, SAID DRY GROUND TOBACCO, SAID CELLULOSE DERIVATIVE, AND A MINOR AMOUNT OF ACID OF THE CLASS CONSISTING OF PHOSPORIC, BORIC AND HYDROXYLATED POLYBASIC CARBOXYLIC ACIDS. 